Blood flows against gravity in the arms and legs and other body parts and is prevented from flowing back by

Options :
  1. the extremely low pressure of venous blood
  2. valves
  3. movements in the surrounding muscles
  4. the narrowing down of the lumen of veins by the contraction of the muscle layer comprising their walls

Answer and Explanation :-

Answer: Option 2


Sorry there is no explanation for this answer. Please help others by posting your response below

How do you rate this queston?  Very Easy  Easy  Average  Above Average  Tough

Previous Question : In order to cure certain diseases of blindness, which part of the donor's eye is used for grafting?

Next Question : Which of the following is the average weight of a human male brain?

Click here for free online test on General Science


 (Getemail alerts when others member replies)

If bringing down the wall would require you to fly, you must believe you can fly. Otherwise, when the decisive moment comes, you will surely discover you ahve no wings.
-Patrick Carman The Dark Hills Divide